Zinc base alloy



- mused; stews,

UNITED 1 sTATlls My invention, which relates to zinc base alloys, and has amons its objects the provision on zinc base alloy of improved characteristics. will be best understood trom the following description, the scope of the invention being more partici larly pointed out in the appended cl.

Serial No. new

tsunamiin all these respects. defects imparted by the aluminum it has been found cannot be satisfactorily eliminated by adding copper. with the aluminum. However. it has been iound that the combination of silver and copper "when added to the Blue with the aluminum, with- The alloys according to the present invention consist of additions to zinc of lto 5% copper. 0.1!0 0.75% aluminum. and 0.03 to 0.5% silver, mun-honed to each other as hereinafter. specifil 'that'by adding to zinc mm amounts of copper. aluminum and silver in proper proportions within the above specified ranges the zinc is given an exceedingly high tensile strensth, the resultina alloy further having excellent hot working properties and resistance to impact loadin: or shock, coupled with freedom from interzranular corrosion and with satisfactory stability with age in respect to maintaining its tensile strength. resistance to shock, and dimensions. Although the ductility of the alloy is not as msn as that 01 some zinc base alloys, it nevertheless is sumciently hish to be satisfactory for many uses, particularly where an alloy is required for fabricating by hot working an article or high unit strength. I

The improved alloys it is believed have tensile strengths superior to any high content Zinc base alloy yet produced. In this respect the alloys in the ranges and proportions herein specified,

has the-remarkable eflect oi!v compensating for these defects tended to be imported by the aluin that it 'efiectively prevents intercrys talline corrosion, alloy phase change and dimensional instability, and improves the ductility in the unaged, annealed and aged conditions an! flciently to make the resulting allcysatisfactoryin that respect for many uses. her, the addition of silver acts very markedly to increase the resistance of the alloy to shock and impact lood ins as compared to pure zinc or zinc which has aluminum alone or both copper and aluminum added to it, and therefore in that respect iurther increases the usefulness oi the alloy.

lug, forging, etc., the improved alioro are still i Although best suited for hotworu by rollsuillciently ductile in the cold condition for light stamping. and drawing operations. They hever find their greatest field of useiulness where with low amounts oi. alloying contents are comparable to high tensile strength forging brass, and with high amounts oi alloying contents are much superior to forging brass and are compare ble to aluminum bronze. For example, the alloy with 5% copper, 0.75% aluminum. and as little as 0.1% silver has a tensile strensth 0! about 68,000 pounds per square inch. If the amount of aluminum in vthis alloy is reduced to 0.1% the alloywill still have a very high tensile strength or 60.000 pounds per square inch. and even it the amountcoi copper is reduced to 1% will still ditional alloy phase to make it unstable in re thus makins the alloy on speot to dimensions,

stshie alloys of very high tensile strength d resistance to shock are required for making hot iorged articiee.

Within the ranges oi constituents herein specifled the above properties of the alloy will he seemed provided the sum oi the amounts oi silver and aluminum does not substantially exceed the amount of copper, and, when the amount of copper is 1.0% or less, the amount of silver does not substantially exceed the amount of aluminum. If the sum of the amounts or silver and aluminum present in the zinc substantially exceeds the amountoi copper present the resuitina alloy will be unsatisi'ectorily deficient in respect to ductility. and may be corrosion and dimensional instability as the alloy ages. If the amount of copper is approxi mately 1.5% or less, and the amount of silver present substantially exceeds the amount of alwminum present, the alloy further will be deficient in tensile strength and lack satisfactory stability in that respect as the alloy.ages. In respect to the amount of silver added, best results will be secured when the silver is within the range or 0.07 to 0.25%. The tensile strength oi? the alloy increases with the amounts or copper or aluminum added, and the ductility decreases with these amounts. Best results in respect to te subject to intersramilar 2' assesses not percentage amount 0! aluminum, the balance hein: substantially zinc.

' 2.21m: base alloys having, approximately, 1 to 5% copper, 0.1 to 0.75% aluminum, and 0.0? to 0.25% silver, the percentage amount 01 silver substantially exceeding the percentage amount of aluminum when the amount, of copadded for modifying the properties of the alloy or securing additional properties, so long as the characteristic properties imparted by the addition 0! copper, aluminum and ilver to the zinc are not substantially destroyed.

1 claim:

per is substantially less than 1.5%, the balance beinz substantially zinc.

3. Zinc base alloys having, approximately, 1

' m 25% copper, 0.1 to 0.4% aluminum, om to LZlnc base alloys having, approximately, 1

to 5% copper, 0.1 to 0.75% aluminum, 0.03 to 0.5% silver, the sum or the percentage amounts of aluminum and silver not substantially exceedins the percentage amount of copper, and, tor

. amounts of copper up to 1.5%, the percentase amount 0: silver not substantiallyexceedins the 2 0.4% silver, the percentage amount or silver not substantially exceeding the percentage amount of aluminum when the-amount of copper is substantially less than 1.5%, the balance being substantially zinc,

-. ,4. Zinc base alloys having, approximately, 3

to 5% copper, 0.8 to-0.I5% aluminum, 0.0? to 05% silver. the balance being substantially zinc.

. EDWARD S. BUNN. 

